House conservatives vowed Thursday to slash domestic programs well beyond the already steep spending cuts promised by GOP leaders in the midterm election campaign that put Republicans in control of the chamber.

WASHINGTON — House conservatives vowed Thursday to slash domestic programs well beyond the already steep spending cuts promised by GOP leaders in the midterm election campaign that put Republicans in control of the chamber.

A proposal unveiled by the Republican Study Committee, whose conservative members make up about three-fourths of the House GOP conference, called for bringing domestic agency budgets down to the 2006 levels in place when Republicans last controlled Congress. That's about a $175 billion cut from current levels and roughly $90 billion more than the cuts promised by Republicans last fall.

Behind the scenes, conservatives are pressuring GOP leaders to deliver on a promise to immediately pass legislation cutting Cabinet budgets by $100 billion this fiscal year, which began Oct. 1 and is already one-third over. Agencies have been operating at 2010 rates and will at least until a stopgap spending bill expires March 4.

"Despite the added challenge of being four months into the current fiscal year, we still must keep our $100 billion pledge to the American people," the committee said in a draft leader to House Speaker John Boehner, R-Ohio.

The letter had not been delivered Thursday. But it posed a potential headache for Boehner, foreshadowing a possible split between tea party-backed freshmen lawmakers and more experienced lawmakers willing to settle for fewer — but more realistic — cuts.

The study committee proposed eliminating several programs outright, including the Legal Services Corporation, which provides legal help to people who can't afford a lawyer; Amtrak subsidies; community development grants popular with local officials, and economic aid to Egypt. It advocated a five-year pay freeze for federal workers, and cutting the federal work force by 15 percent through attrition.

"The pledge, the $100 billion, is simply a start," freshman Rep. Mick Mulvaney, R-S.C., said. "We want more. We will be looking for ways to cut the deficit and the debt more than is in the pledge."

Senior Republicans on the House Appropriations Committee, meanwhile, were working on the already difficult task of fulfilling the party's original promise to take most domestic agencies other than the Homeland Security and Veteran Affairs departments down to their 2008 spending levels. That would require cutting their operating budgets an average 18 percent, or about $84 billion, from last year's budget.

"These are not going to be easy cuts," House Appropriations Committee Chairman Harold Rogers, R-Ky., said.

While conservatives are pressing for deeper cuts, appropriators are looking to protect the budgets for agencies such as NASA, the FBI and the Indian Health Service.

"I suspect what they're going to do is give us a number to hit — that we have to reduce our budget by X number of dollars," said Rep. Mike Simpson, R-Idaho, who will chair the panel responsible for the Interior Department, Indian health care and the Environmental Protection Agency. "And then some areas will see larger cuts, and some areas we'll be able to protect to some degree."

Simpson cited the Bureau of Indian Affairs and the Indian Health Service as programs he wants to try to protect.

Conservatives have already balked at their senior colleagues' plan. On Wednesday, tea party favorite Rep. Tim Scott, R-S.C., successfully removed language promising a "transition" to 2008 levels from a symbolic resolution affirming the campaign promise and scheduled for a House vote hours before President Barack Obama's State of the Union speech to Congress next Tuesday.

Scott's move was in keeping with demands by freshmen and conservatives to adhere to the $100 billion promise even though the fiscal year is well under way. Meeting that goal would require large-scale layoffs of federal workers.

The White House warned that immediate cuts of that magnitude would measure about one-third of the budgets of most Cabinet departments. The cuts could force almost 400,000 children from Head Start, reduce the size of Pell Grants for low-income students by an average $1,000, and force the Justice Department to furlough 4,000 FBI agents and 900 U.S. marshals.

There's no stomach in the Democratic-controlled Senate for cuts even remotely approaching those sought by House Republicans. In fact, Senate Democrats may have the upper hand simply by passing stopgap bills at current spending levels, which they could deliver to the GOP-dominated House as a take-it-or-leave-it proposition. A rebuke by the House of such legislation could spark a shutdown of the government.

GOP leaders say their goal is cutting spending and not shutting down the government. A partial shutdown in 1995 and 1996 hurt congressional Republicans politically and bolstered Democratic President Bill Clinton.

Also Thursday, Republicans announced that the House will vote next week on abolishing the system of financing presidential candidates and national conventions with federal matching funds, a measure that would save $520 million over a decade if passed and signed into law.